How do you work out Empirical Formula?

I struggle with chemistry, especially formulas because i can't do maths either...so if you answer my questions please could you do it very clearly and if possibly simply?

Posted Sat 20th October, 2012 @ 17:04 by Stargirl
Edited by Stargirl on Sat 20th October, 2012 @ 17:04

For example, you could have two masses or percentages like 27.3% carbon and 72.7% oxygen.

You first divide each mass by its relative atomic mass so carbon's is 12 and oxygen's is 16.

27.3/12 = 2.275          72.7/16 = 4.55

You then divide them all by the smallest:

2.275/2.275 = 1          4.55/2.275 = 2

So therefore, you need 1:2 C:O ratio which is CO2

This may explain it easier:

http://www.creative-chemistry.org.uk/gcse/documents/Module7/N-m07-10.pdf

Answered Sat 20th October, 2012 @ 19:41 by Joanne

thank you so much! that does help actually and i'll have a look at the site :)

Answered Sun 21st October, 2012 @ 10:11 by Stargirl

No problem! Just remember the steps:

1) divide the masses by their relative atomic masses

2) divide these results by the smallest result

3) put the numbers into a ratio and it gives how many of each element you need

:)

Answered Sun 21st October, 2012 @ 13:21 by Joanne